angiogenesis factor a substance that causes the growth of new blood vessels, found in tissues with high metabolic requirements such as cancers and the retina. It is also released by hypoxic macrophages at the edges or outer surface of a wound and initiates revascularization in wound healing.

2. a preparation of factor VIII administered intravenously for the prevention or treatment of hemorrhage in patients with hemophilia A and the treatment of von Willebrand disease, hypofibrinogenemia, and coagulation factor XIII deficiency. Included are preparations derived from human plasma (antihemophilic factor, cryoprecipitated antihemophilic factor) or porcine plasma (antihemophilic factor [porcine]) and those produced by recombinant technology antihemophilic factor [recombinant]).

atrial natriuretic factor (ANF) a hormone produced in the cardiac atrium; an inhibitor of renin secretion and thus of the production of angiotensin, and a stimulator of aldosterone release. Its effect is increased excretion of water and sodium and a lowering of blood pressure.

factor B a complement component that participates in the alternative complement pathway.

C3 nephritic factor (C3 NeF) an autoantibody that stabilizes the alternative complement pathway C3 convertase, preventing its inactivation by factor h, resulting in complete consumption of plasma C3; it is found in the serum of many patients with type II membranoproliferative glomerulonephritis.

hematopoietic growth f's a group of substances with the ability to support hematopoietic colony formation in vitro, including erythropoietin, interleukin-3, and colony-stimulating factors. All except erythropoietin stimulate mature cells, have overlapping capabilities to affect progenitor cells of several blood cell lines, and also affect cells outside the hematopoietic system.

histamine-releasing factor (HRF) a lymphokine, believed to be produced by macrophages and B lymphocytes, that induces the release of histamine by IgE-bound basophils. It occurs in late phase allergic reaction, six or more hours after contact with the antigen, in sensitive individuals.

homologous restriction factor (HRF) a regulatory protein that binds to the membrane attack complex in autologous cells, inhibiting the final stages of complement activation.

factor I a plasma enzyme that regulates both classical and alternative pathways of complement activation by inactivating their C3 convertases.

immunoglobulin-binding factor (IBF) a lymphokine having the ability to bind IgG complexed with antigen and prevent complement activation.

insulinlike growth f's (IGF) insulinlike substances in serum that do not react with insulin antibodies; they are growth hormone–dependent and possess all the growth-promoting properties of the somatomedins.

intensification factor in radiology, the comparative increase in light transmission when films are exposed in the presence of intensifying screens compared to that in the absence of screens.

intrinsic factor a glycoprotein secreted by the parietal cells of the gastric glands, necessary for the absorption of cyanocobalamin (vitamin B12). Its absence results in pernicious anemia.

LE factor an immunoglobulin that reacts with leukocyte nuclei, found in the serum in systemic lupus erythematosus.

lymphocyte mitogenic factor (LMF) (lymphocyte-transforming factor) a substance that is released by lymphocytes stimulated by specific antigen and causes nonstimulated lymphocytes to undergo blast transformation and cell division; called also blastogenic factor.

minification factor in radiology, the gain in light achieved by a reduction in size of the output phosphor from the input phosphor size.

osteoclast-activating factor (OAF) a lymphokine that stimulates bone resorption; it may be involved in the bone resorption associated with multiple myeloma and other hematologic neoplasms or inflammatory disorders such as rheumatoid arthritis and periodontal disease.

platelet-activating factor (PAF) a substance released by basophils and mast cells in immediate hypersensitivity reactions, and by macrophages and neutrophils in other inflammatory reactions; it leads to bronchoconstriction, platelet aggregation, and release of vasoactive substances from platelets.

releasing f's factors elaborated in one structure (as in the hypothalamus) that effect the release of hormones from another structure (as from the anterior pituitary gland), including corticotropin-releasing factor, melanocyte-stimulating hormone–releasing factor, and prolactin-releasing factor. Applied to substances of unknown chemical structure, while substances of established chemical identity are called releasing hormones.

Rh factor a type of agglutinogen found on some erythrocytes; see also rh factor.

rheumatoid factor (RF) antibodies directed against antigenic determinants on IgG molecules, found in the serum of about 80 per cent of patients with classic or definite rheumatoid arthritis; but in only about 20 per cent of patients with juvenile rheumatoid arthritis; rheumatoid factors may be IgM, IgG, or IgA antibodies, although serologic tests measure only IgM. Rheumatoid factors also occur in other connective tissue diseases and infectious diseases.

risk factor an agent or situation that is known to make an individual or population more susceptible to the development of a specific negative condition.

risk factor (omaha) an environmental, psychosocial, or physiologic event or health related behavior that increases the client's exposure or vulnerability to the development of a client problem; the nurse's knowledge base of risk factors is used to identify potential problem modifiers in the Problem Classification scheme of the omaha system.

transfer factor (TF) a factor occurring in sensitized lymphocytes that can transfer delayed hypersensitivity to a formerly nonreactive individual; see also transfer factor.

tumor necrosis factor (TNF) either of two lymphokines produced primarily by cells of the immune system, capable of causing in vivo hemorrhagic necrosis of certain tumor cells but not normal cells. They also destroy cells associated with the inflammatory response. They have been used as experimental anticancer agents but can also induce shock when bacterial endotoxins cause their release. Tumor necrosis factor α, formerly called cachectin, contains 157 amino acids and is produced by macrophages, eosinophils, and NK cells. Tumor necrosis factor β is lymphotoxin and contains 171 amino acids.

vascular endothelial growth factor (VEGF) (vascular permeability factor (VPF)) a peptide factor that stimulates the proliferation of cells of the endothelium of blood vessels; it promotes tissue vascularization and is important in blood vessel formation in tumors.

von Willebrand's factor (vWF) a glycoprotein synthesized in endothelial cells and megakaryocytes that circulates complexed to coagulation factor VIII. It is involved in adhesion of platelets to damaged epithelial surfaces and may participate in platelet aggregation. Deficiency results in the prolonged bleeding time seen in von Willebrand's disease.

fac·tor III

in the clotting of blood, tissue factor or thromboplastin; it initiates the extrinsic pathway by reacting with factor VII and calcium to form factor VIIa. See: thromboplastin.

factor III

obsolete designation for a membrane protein found normally in subendothelial tissue. When exposed to blood, it forms a complex with factor VIIa to activate extrinsic coagulation. Now called tissue factor.

factor III

Tissue factor, see there, aka thromboplastin.

fac·tor III

(fak'tŏr)

In the clotting of blood, tissue factor, or thromboplastin, initiates the extrinsic pathway by reacting with factor VII and calcium to form factor VIIa. See also: thromboplastin

fac·tor III

(fak'tŏr)

In the clotting of blood, tissue factor, or thromboplastin, initiates the extrinsic pathway by reacting with factor VII and calcium to form factor VIIa.

The other two factors are composed of the items belonging to the Anxiety scale originally proposed: a set of three items related to distress and generalized nervousness integrate Factor III, and three items that assessed panic symptoms comprise Factor IV.

Factor II has been identified as Beyond Essential Elements with 12 items; Factor III was labeled Motivation and Rewards for Teaching generated from four items; and Factor IV was inferred from four items: Pride and self esteem.

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